Blood stains showed George Button had been the victim of an attack, not a hit-and-run accident, an expert told a murder trial jury.

Mr Button, 53, a council electrician, was found dying of horrific head injuries, after taking his dog for a walk along an unlit lane, near his home in West Rainton, County Durham.

Police investigators and even a pathologist first thought Mr Button had probably been knocked down by a car or truck, Newcastle Crown Court has heard.

But forensic scientist, Dr Gemma Escott, told the jury the pattern of blood stains on the victim's jacket showed his head had been struck several times.

"Looking at the situation where there are two blows, and more likely three, around the same part of George Button's head, I find it really hard to envisage that as part of a road traffic accident, particularly without any other debris at the scene," Dr Escott said. "In my view George Button was assaulted rather than struck by a motor vehicle."

Mr Button's wife, Christina, 32, and her live-in nephew, Simon Tannahill, 20, both deny his murder in March this year.

Prosecutors claim Tannahill was besotted with his aunt, who had tired of her much older husband and stood to collect more than &#xA3;450,000 in life insurance pay-outs from his death.